The present invention relates to a method of preparing alkaline difluoromethane sulfonates. More particularly, it concerns the preparation of alkaline difluoromethane sulfonates from chlorodifluoromethane.
In the prior art [J. Chem. Soc., pp. 3058-3062 (1960)], a method is disclosed for preparing sodium difluoromethane sulfonate by reacting chlorodifluoromethane with sodium sulfite in aqueous solution at 120.degree. C. in an autoclave. When operating for 20 hours under an autogenous pressure of 16 bars, the yield indicated in the said publication is 23 percent. In a test carried out by the present applicant, under the same conditions, there was obtained a conversion of only 4.4 percent of the chlorodifluoromethane, with a sodium difluoromethane sulfonate selectivity of 10 percent, which is equivalent to a total yield of only 0.4 percent.
The present applicant has now discovered a method which alleviates the drawbacks of said prior art. The method of the present invention makes it possible to obtain conversion rates of the chlorodifluoromethane and selectivities for alkaline difluoromethane sulfonate which provide a process worthy of interest on an industrial scale. These are important objects of the present invention.
Another object of the present invention is, therefore, to provide an improved method of preparing alkaline difluoromethane sulfonates.
Other objects will be apparent to those skilled in the art from the present description.